It is important to ask the following questions before deciding to substitute a silicone sealant:Will the alternative sealant be applied for structural glazing?
Will the alternative sealant need to be weather / UV exposed?
What is the expected movement capacity required?
Will the finishing be covered or not?
The answers to these will dictate the best solution. Discuss these items with your product manufacturer to identify their suggested alternatives.

How do I repair a failed silicone sealant joint without silicone?There are a couple of ways to repair a failed silicone sealant joint with polyurethane technology. However, since polyurethanes will not develop adhesion to cured silicones, the existing silicone sealant would need to be fully removed. If the joint is located within a porous substrate, this substrate will likely need some mechanical abrasion to remove as much of the existing sealant as possible. If the sealant joint is in a non-porous substrate, the sealant should be cut out as close as possible to the bond line. Sanding with a fine grit sandpaper may be needed to remove any silicone that is left within the joint.When applying the new polyurethane sealant joint, it is recommended that the polyurethane extend ¼ inch (6.35 mm) onto the substrate on either side of the joint. This will ensure the material is bonding to fresh substrate.